© December 2020| IJIRT | Volume 7 Issue 7 | ISSN: 2349-6002 IJIRT 150560 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 252 Application of Microcontroller in Door Locking System and Smart Home Harsh Verma 1 , Shripad G. Desai 2 1 Student, Department of Electrical Engineering, Bharati Vidyapeeth (Deemed to Be University), College of Engineering, Pune, India 2 Assistant Professor, Department of Electrical Engineering, Bharati Vidyapeeth (Deemed to Be University), College of Engineering, Pune, India Abstract - Microcontrollers have variety of applications. Microcontrollers are used in automatically controlled products and devices. One such application is the use of microcontrollers in door locking system. The fundamental use of this project is to provide security in houses, ATM etc. So, the system works in such a way that first we need to set a password which then gets stored in the database. Whenever the correct password will be entered with the help of keypad the controller will send instruction to the DC motor and the door will be unlocked. This electronic technology can be used to create a fully customized and personalized door locking system. Smart homes are gaining importance with time as they have become more advanced and reliable. To make life easier, the user can switch off all the appliances while going out just by a touch from the smart phone. INTRODUCTION Many a times we forget to carry our house keys or misplace the keys wherever we go. Sometimes the door latches close automatically [4]. In such conditions it is not an easy task to open the door. Thus, if door latch can be opened using a password entered with the help of a keypad then the owner will not need to carry house keys and has to just remember the password. People are facing certain security issues all over the world. The main component in door locking system is the 8051 microcontrollers. A 4*4 Matrix keypad is used to enter password. Then are the entered password matches with the one stored in the database the door gets unlocked. Further the status of the door is displayed on the LCD screen connected to the circuit [7]. If wrong passcode is entered for 3 times the alarm rings. The door locking system is controlled by the 8-bit microcontroller 8051 which has a 2Kbytes of ROM for the program memory [8]. The password is saved in the EPROM so that we can change it at any time. This 8- bit controller requires a supply voltage of +5V DC. COMPONENTS 1. Microcontroller: it is the central processing unit (CPU) of the door locking system. The 8051 has a number of applications, such as: a. Reading the digital input from the keypad. b. Sending the data to LCD so that the person operating the system can read the instruction. c. Sensing the password using keypad and to check whether it is a correct password or a wrong password and rotate the stepper motor if the password entered is correct. 2. LCD: we are going to use an alphanumeric liquid crystal display (LCD). This means that it can display alphabets and numbers 3. Buzzer: the buzzer is used to buzz the alarm if the password is entered incorrectly. 4. Keypad: the password is entered using keypad in the system to unlock the door system. A 4x4 keypad is used in our system for input. MOTOR DRIVER IC (L293D) The Actuator's are those devices which actually gives the movement or to do a task like DC motor. There are various types of motors available which works on different voltages thus, we need motor driver for running the microcontroller. To get interface between motor and microcontroller [4] we use L293D motor driver IC in our circuit. To simplify use as two bridges each pair of channels is equipped with an enable input. A separate supply input is provided for the logic, allowing operation at a